Various styles of carrying bags are available. One popular style is a duffel bag, which tends to be generally rectangular, tubular or cylindrical and is carried using a long shoulder strap or shorter straps for hand-carry. Another popular style is a cross-body bag, also referred to as a messenger-style bag. A cross-body bag generally has a strap that is worn over one shoulder, diagonally across the body to the waist or hip opposite the carrying shoulder, with the bag resting against the back or the rear of the hip.
A duffel bag with a sufficiently long strap can be draped across the body, but carrying a duffel bag in this way can present challenges (e.g., comfort, load management, bag positioning, etc.). That is, often the shape of the bag influences how the bag sits against the body and the distribution of the contents of the bag, both of which can make a typical duffel bag less than perfect to carry across one's body. If a duffel bag is donned, it is typically worn in a backpack configuration, with straps over both shoulders, and the duffel bag oriented vertically, generally along the spine of the person wearing the bag.
A person selecting and carrying a bag may wish to have the capacity and carrying options of a duffel bag, but also wish to be able to wear the bag in a cross-body configuration under certain circumstances. For example, a duffel bag may be more convenient when carrying certain types of items, and the compact, generally uniform size of the duffel bag is useful for stowing the bag or otherwise securing to a rack. On the other hand, a messenger bag may be more convenient if walking, jogging, biking, skateboarding, roller-skating or otherwise traveling in a manner where the bag must be carried rather than stowed. It may be inconvenient to transfer bag contents between a duffel bag and a cross-body bag depending on travel circumstances.